Results 51 to 60 of about 146,288 (166)

Solar Activity Impacts on Ionospheric Scintillation and Precise Point Positioning Based on Multi‐Year GNSS and Scintillation Observations

Space Weather, Volume 24, Issue 3, March 2026.
Abstract Solar activity induces ionospheric irregularities that degrade Global Navigation Satellite System (GNSS) performance through amplitude and phase scintillation. Although numerous studies have investigated event‐driven or regional responses, the nonlinear coupling between solar radiation, ionospheric scintillation, and precise point positioning (
Jincheng Li, Qi Liu, Xiaomin Luo, Manuel Hernández‐Pajares, Enric Monte‐Moreno, Guangxia Wang, Heng Yang, Chuanding Zhang, Li Yang, Yaoyao Liu   +9 more
wiley   +1 more source

The effects of stellar winds on the magnetospheres and potential habitability of exoplanets [PDF]

, 2014
V.S. acknowledges the support of an STFC studentship. A.A.V. acknowledges support from a Royal Astronomical Society Fellowship and an Ambizione Fellowship from the Swiss National Science Foundation. S.V.J.
S. C. Marsden, Jeffers, Sandra V., P. Petit, S. V. Jeffers, Jardine, M., M. Jardine, A. A. Vidotto, Vidotto, A. A., Petit, P., V. See, Do Nascimento, J.D., J. D. do Nascimento, do Nascimento, Jose-Dias Jr., do Nascimento Jr., J. D., Jeffers, S.V., See, Wyke Chun Victor, Vidotto, A.A., Marsden, S. C., See, V., Jeffers, S. V., Marsden, S.C.   +20 more
core   +1 more source

The Near-infrared Ca ii Triplet as a Stellar Activity Indicator: A Library and Comparative Study

The Astrophysical Journal Supplement Series
We have established and released a new stellar index library of the Ca ii triplet, which serves as an indicator for characterizing the chromospheric activity of stars.
Xin Huang, Yuji He, Zhongrui Bai, Hailong Yuan, Mingkuan Yang, Ming Zhou, Yiqiao Dong, Mengxin Wang, Han He, Jinghua Zhang, Yaoquan Chu, Yongheng Zhao, Yong Zhang, Haotong Zhang   +13 more
doaj   +1 more source

A New Method for Probabilistic Spatiotemporal Forecasts of Solar Soft X‐Ray “S‐Class” (>X10) Superflares

Journal of Geophysical Research: Space Physics, Volume 131, Issue 2, February 2026.
Abstract Solar superflares of S‐class (>X10 in soft X‐rays) pose extreme space weather hazards, yet their prediction remains a fundamental challenge owing to their rapid and transient natures and the limitations of conventional event‐based forecasts. We introduce for the first time, a probabilistic spatiotemporal framework designed to identify extended
V. M. Velasco Herrera, G. Velasco Herrera, W. Soon, A. Özgüç, N. Babynets, A. Tlatov, M. Švanda, S. Qiu, S. Baliunas, B. Kotan, G. González González, L. A. Bautista Flores, M. Pazos   +12 more
wiley   +1 more source

Nature of HD 251108: An RS CVn Binary with a Long-term Evolving Spot

The Astrophysical Journal
Recently, the Lobster Eye Imager for Astronomy detected the longest-lasting and most energetic stellar X-ray flare event from HD 251108. In this work, we redetermined the atmospheric parameters of HD 251108 using three spectroscopic observations obtained
Xinlin Zhao, Song Wang, B. Fuhrmeister, J. H. M. M. Schmitt, Xuan Mao, He-Yang Liu, Xiaohong Yang, Jifeng Liu   +7 more
doaj   +1 more source

The High-energy Spectrum of the Young Planet Host V1298 Tau

The Astronomical Journal, 2023
V1298 Tau is a young pre-main-sequence star hosting four known exoplanets that are prime targets for transmission spectroscopy with current-generation instruments. This work pieces together observations from the NICER X-ray telescope, the Space Telescope
Girish M. Duvvuri, P. Wilson Cauley, Fernando Cruz Aguirre, Roy Kilgard, Kevin France, Zachory K. Berta-Thompson, J. Sebastian Pineda   +6 more
doaj   +1 more source

Space Weather Impact of Three Solar Flares Observed by the POEMAS Telescope at 45 and 90 GHz

Journal of Geophysical Research: Space Physics, Volume 130, Issue 11, November 2025.
Abstract Solar flares are often associated with coronal mass ejections (CMEs) that, when directed toward Earth, can disrupt the magnetosphere and impact space weather. In this study, we investigate three long‐duration solar flares observed in 2012 by the POlarization Emission of Millimeter Activity at the Sun (POEMAS) telescopes at 45 and 90 GHz.
Adriana Valio, Karla F. Lopez, José Luis Gamonal Valenzuela, Ruben M. Romero Ramírez, Dougas F. da Silva   +4 more
wiley   +1 more source

Stellar activity with LAMOST – II. Chromospheric activity in open clusters [PDF]

Monthly Notices of the Royal Astronomical Society, 2018
21 ...
Fang, Xiang-Song, Zhao, Gang, Zhao, Jing-Kun, Kumar, Yerra Bharat   +3 more
openaire   +2 more sources

Predicting Photospheric Ultraviolet Emission from Stellar Evolutionary Models

The Astrophysical Journal
Stellar ultraviolet (UV) emission serves as a crucial indicator for estimating magnetic activity and evaluating the habitability of exoplanets orbiting stars.
Song Wang, Xue Li, Henggeng Han, Jifeng Liu   +3 more
doaj   +1 more source

Solar Flare Activity, 1937–2024: Introducing the New Hemispheric Solar Flare Index (hSFI) in the Context of 2024's Major Solar Storm Events

Space Weather, Volume 23, Issue 11, November 2025.
Abstract A new daily composite of the solar flare index (SFI) and the hemispherically‐resolved versions (hSFI) are presented for 1937 to 2024. The data set confirms that the northern hemisphere (NH) dominated solar flare activity during Solar Cycles 17 to 21, but that the southern hemisphere has dominated from Solar Cycle 22 to present.
V. M. Velasco Herrera, W. Soon, S. Knoška, A. Özgüç, G. Velasco Herrera, H. Yeşilyaprak, N. Babynets, M. Švanda, J. Muraközy, S. Qiu, D. Riveros‐Rosas, R. Connolly, M. Connolly, A. Tlatov, L. Cappellotto   +14 more
wiley   +1 more source